In conventional gas-blast circuit-breakers a high degree of turbulence is considered essential for rapid current interruption. Turbulence increases the arc heat losses, and these heat losses lead to a more constricted, or smaller arc; and a smaller arc can dielectrically recover much more quickly leading to its extinction.
Those skilled in the art of circuit interruption are well aware of many circuit-interrupting devices which utilize a rotating magnetic field to cause rotation of the arc column about the separable contacts. This gives rise to a greater interaction between the arc itself and the surrounding arc-extinguishing ambient, which may be a gas-blast, projected by suitable compressing means, through an orifice opening. Reference is made to U.S. patents: Wilson, U.S. Pat. No. 3,716,685, issued Feb. 13, 1973; Beatty et al., U.S. Pat. No. 3,418,440, issued Dec. 24, 1968; Robinson et al., U.S. Pat. No. 3,469,050, issued Sept. 23, 1969; and Beatty, U.S. Pat. No. 3,274,365, issued Sept. 20, 1966, as typical examples of the application of radial magnetic field coils, which effect a rotative travel of an established arc during interruption. In addition, reference is made to Stone, U.S. Pat. No. 2,166,828, issued July 18, 1939, which illustrates the interaction of a direct-current magnetic field acting upon an alternating-current power arc resulting in an oscillating movement of the established arc in the Stone device and its consequent interruption.
Also of interest is Joseph Slepian, U.S. Pat. No. 2,103,121, issued Dec. 21, 1937, which shows a series field-coil, electrically connected in series with the circuit-interrupting contacts and effecting a consequent rotation of the established arc between a pair of tubular, cooperable, relatively-movable contacts, while at the same time utilizing a gas-blast to assist in arc interruption.
It will, however, be noted that the aforesaid circuit-interrupting structures, as exemplified by the foregoing patents, do not use a transitory high-frequency magnetic field, with which the present invention is particularly concerned.